Prices in new york and singapore

Hello everyone, I'll be travelling to Singapore and New York in a couple of weeks (from Sydney) and would like to know more about the shopping. Â Specifically, does anyone know if there's a huge price difference between NY and Singapore for designer gears? I'm looking at spending some serious money on Marc Jacobs, Helmut Lang, Prada, Miu Miu and Dior Homme. Any advice is greatly appreciated. Thanks in advance.